Insulating Film Structure for LCD Electric Field Control
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Solution Overview
Problem
Active-matrix-type liquid crystal display devices face challenges in controlling liquid crystal molecule alignment due to electric field interference from source lines, leading to reduced display quality and transmittance.
Innovation Solution
The design incorporates a specific configuration of insulating films and electrodes, where the fourth insulating film has a greater thickness than the third, and a relationship between their relative dielectric constants is maintained to suppress unwanted electric fields, enhancing the electric field formation and reducing interference from source lines, while ensuring the pixel potential is maintained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional single-layer insulating film structure is used, then the device complexity is low, but electric field interference from source lines increases causing image crosstalk and reduced display quality
Solution Approach 1:
The patent divides the insulating film structure into multiple layers (first insulating film, second insulating film, third insulating film) with different dielectric constants and thicknesses. Each layer serves a specific function in managing electric fields: the first layer (higher dielectric constant) suppresses fields from source lines, the second layer provides intermediate insulation, and the third layer completes the insulating structure. This segmentation allows precise control of electric field distribution to reduce image crosstalk while maintaining manageable device complexity.
2Object-affected harmful factors
If the thickness of insulating films is increased to reduce electric field interference, then electric field suppression improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent specifies precise parameter relationships between the insulating film layers to optimize electric field suppression while controlling manufacturing complexity. Specifically, the dielectric constant ratio (K1/K2) is set between 1.05-2.0, and the thickness ratio (d1/d2) is set between 0.5-2.0, where K1 and K2 are dielectric constants of the first and second insulating films, and d1 and d2 are their respective thicknesses. These parameter constraints provide a balanced design space that achieves effective electric field interference reduction while remaining feasible for manufacturing.
3Object-affected harmful factors
If a double-layer pixel electrode is arranged between source lines, then electric field interference is reduced, but the area of the pixel electrode decreases
Solution Approach 1:
The patent introduces insulating films as intermediary elements between the source lines and the pixel electrode. Rather than repositioning or redesigning the pixel electrode structure, the insulating films act as a mediating layer that modifies the electric field distribution in the space between source lines and pixel electrode. This approach reduces electric field interference without requiring changes to the pixel electrode's position or area, thereby maintaining display area while achieving interference reduction.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves display quality by reducing image crosstalk and enhancing transmittance, maintaining pixel potential stability, and allowing for better alignment of liquid crystal molecules, thus improving the overall display performance.
Implementation Method 1
a fourth insulating film which covers the source line and the drain electrode and which has a thickness greater than a thickness of the third insulating film
Implementation Method 2
technology of controlling alignment of liquid crystal molecules by a lateral electric field or an oblique electric field formed between a pixel electrode and a common electrode
Data Source
AI summary
According to one embodiment, a display device includes a semiconductor layer, a first insulating film covering the semiconductor layer, a gate line extended in a first direction on the first insulating film to intersect the semiconductor layer, a second insulating film covering the gate line, a first common electrode formed on the second insulating film, a third insulating film covering the first common electrode, a source line which is extended in a second direction on the third insulating film and which is in contact with the semiconductor layer, and a fourth insulating film which covers the source line and which has a thickness greater than a thickness of the third insulating film.